Localization of Smad4 (A), Smad7 (B),) and Smad6 (C), c-Ski (D) and TGIF (E) in lens epithelial (LE) and fiber cells (LF). Nuclear localization of Smad4 and TGIF is seen mainly in lens fiber cells. Smad7 is seen in the nuclei of both epithelial and fiber cells, although staining is stronger in fiber cell nuclei. Both I-Smads, Smad7 and Smad6, are abundant in the cytoplasm of lens epithelial cells. c-Ski is found mainly to the cytoplasm. A-C are sections of E7 chicken lenses and D-E are P3 mouse lenses.